I didnt catch it very clearly and i am going to go on my DVR later and check but i dont think that the symbol on the wall was the same one. It might be a different sector. Maybe all the sectors are on different parts of the island to keep something in? i dont know. just a guess. Thats why the walls are so think (as sihid said 8-10 feet thick). there may be something they are keeping in the center.

I'm pretty sure it was the word Dharma with an arrow pointing upward.

Zip

same octagon symbol, but had a cross in the middle and no Dharma either. Thats all I could make out.

Its not the same one, I couldnt get a look at it on the tv, making a screen cap later to check it out

I was trying to see the symbol, too, but it was kinda too far away to see it and they only showed it for a second. Could anyone get us a picture of it?

I looked like a plus sign/cross inside to me. Someone will have screen caps up soon, I'm sure! :D

Not great... but all I can do for now.
http://lost.cubit.net/pics/dharmaLogo2.jpg

There's already a thread about this

http://thefuselage.com/Threaded/showthread.php?t=22369

I posted a pretty good cap of it in there.